CN114200653A

CN114200653A - Off-axis spherical surface collimator optical system

Info

Publication number: CN114200653A
Application number: CN202111526153.6A
Authority: CN
Inventors: 胡明勇; 徐剑锋; 王秀娟
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2021-12-14
Filing date: 2021-12-14
Publication date: 2022-03-18

Abstract

The invention discloses an off-axis spherical surface collimator optical system which comprises a first plano-convex lens, a second plano-concave lens and a third spherical reflector, wherein the curved surfaces of the first plano-convex lens, the second plano-concave lens and the third spherical reflector are all spherical surfaces, and the first plano-convex lens, the second plano-concave lens and the third spherical reflector are all obliquely arranged to correct a light path. The off-axis spherical surface collimator optical system adopts a global off-axis design, has no central barrier, is simpler in processing and detection, avoids the technical problems of difficulty in processing and assembly detection, high cost and the like of an off-axis reflective collimator optical system with a barrier on the same axis, greatly reduces the processing and detection difficulty, and reduces the production cost. Meanwhile, the first plano-convex lens, the second plano-concave lens and the third spherical reflector are all or partially inclined at a certain angle, so that chromatic aberration can be eliminated, the image quality can be corrected, the image quality effect is good, and the field angle is large.

Description

Off-axis spherical surface collimator optical system

Technical Field

The invention relates to the technical field of optical detection, in particular to an off-axis spherical surface collimator optical system.

Background

The collimator optical system is a typical optical calibration system, and is a necessary tool for measuring parameters of the optical system. The system mainly has the advantages that a beam of parallel light is provided to simulate an infinite target, different optical devices can be placed at the focal plane position of the system to detect performance parameters of different tested systems, such as a reticle is placed to measure the focal length of the tested system, and a discrimination plate, a star point plate and other measurement system resolutions and other imaging qualities are placed. Conventional collimator tubes have both on-axis and off-axis forms.

The coaxial collimator tube can cause the problems of small field of view and central obstruction, and has great influence on the imaging quality. The off-axis collimator optical system has no central barrier, so that energy loss can be avoided. The off-axis collimator generally adopts a reflection form, and can realize large aperture, no chromatic aberration, no central shielding and compact structure because the off-axis collimator is not limited by optical materials, thereby being widely used. However, the reflecting surface of the conventional off-axis reflective parallel light pipe optical system generally adopts an aspheric surface, which can improve the image quality well, but the aspheric surface has high processing difficulty and high cost. During subsequent adjustment detection, compared with a common spherical mirror, the aspherical mirror is more difficult, and different types of aspherical mirrors also need specific detection methods. When the caliber is larger, the processing and detection difficulty is further increased, and the cost is higher. Meanwhile, the optical system of the reflective collimator is generally lower than 0.5 degrees, and the field of view is small, so that the test is not facilitated.

Disclosure of Invention

The invention aims to: an off-axis spherical collimator optical system and a detection method thereof are provided to solve the above defects.

In order to achieve the above purpose, the invention provides the following technical scheme:

an off-axis spherical surface collimator optical system comprises a first plano-convex lens, a second plano-concave lens and a third spherical reflector, wherein the curved surfaces of the first plano-convex lens, the second plano-concave lens and the third spherical reflector are all spherical surfaces, the third spherical reflector is obliquely arranged, and the first plano-convex lens and the second plano-concave lens are arranged in a non-parallel mode.

Preferably, the x-field angle and the y-field angle of the off-axis spherical collimator optical system are both +/-1 degree.

Preferably, the incident light is transmitted through the first plano-convex lens and the second plano-concave lens, and finally reflected and focused by the third spherical mirror.

Preferably, the first plano-convex lens and the second plano-concave lens are both made of BK7 material, and the third spherical mirror is made of glass ceramics.

Preferably, the curvatures of the first plano-convex lens and the second plano-concave lens are opposite numbers.

Preferably, the third mirror is tilted at an angle to complete the off-axis design.

The invention has the beneficial effects that:

the invention relates to an off-axis spherical surface collimator optical system, wherein incident light is transmitted through a first plano-convex lens and a second plano-concave lens, and then is reflected by a third reflector to form an image. The system adopts a global off-axis design, has no central barrier, is simpler in processing and detection, avoids the technical problems of difficulty in processing, assembly and detection, high manufacturing cost and the like of an off-axis reflective collimator optical system with a barrier on the same axis, greatly reduces the processing and detection difficulty and reduces the production cost. Meanwhile, the first plano-convex lens is inclined at a certain angle, and the first plano-convex lens and the second plano-concave lens are arranged in a non-parallel mode, so that chromatic aberration can be eliminated, the image quality can be corrected, the image quality effect is good, and the field angle is large.

Drawings

FIG. 1: the invention discloses a light path diagram of an off-axis spherical surface parallel light tube optical system;

FIG. 2: a stippling diagram of the off-axis spherical collimator optical system of embodiment 1;

FIG. 3: the + y field-of-view wavefront difference map of the off-axis spherical collimator optical system of embodiment 1;

FIG. 4: the-y field of view wavefront difference plot of the off-axis spherical collimator optical system of example 1;

FIG. 5: the + x field-of-view wavefront difference map of the off-axis spherical collimator optical system of embodiment 1;

FIG. 6: the-x field of view wavefront difference plot of the off-axis spherical collimator optical system of example 1;

FIG. 7: an off-axis spherical collimator optical system dot diagram of embodiment 2;

FIG. 8: the + y field-of-view wavefront difference map of the off-axis spherical collimator optical system of embodiment 2;

FIG. 9: the-y field of view wavefront difference plot of the off-axis spherical collimator optical system of example 2;

FIG. 10: the + x field-of-view wavefront difference map of the off-axis spherical collimator optical system of embodiment 2;

FIG. 11: the-x field of view wavefront difference plot of the off-axis spherical collimator optical system of example 2.

Detailed Description

The following description of the embodiments of the present invention is made with reference to the accompanying drawings 1 to 11:

as shown in fig. 1, an off-axis spherical collimator optical system includes a first plano-convex lens 1, a second plano-concave lens 2, and a third spherical reflector 3, wherein the curved surfaces of the first plano-convex lens 1, the second plano-concave lens 2, and the third spherical reflector 3 are all spherical surfaces. The third spherical reflector is obliquely arranged, and the first plano-convex lens and the second plano-concave lens are arranged in a non-parallel mode, namely a certain inclination angle is formed between the first plano-convex lens and the second plano-concave lens, so that light transmission and light path correction are facilitated. The incident light is transmitted through the first plano-convex lens 1 and the second plano-concave lens 2, and is finally reflected and focused by the third spherical reflector 3. The first plano-convex lens 1 and the second plano-concave lens 2 are both made of BK7, and the third spherical reflector 3 is made of microcrystalline glass. The curvatures of the first plano-convex lens 1 and the second plano-concave lens 2 are opposite numbers, and the third spherical reflector 3 is inclined by a certain angle to complete the off-axis design.

Example 1:

when the off-axis spherical surface collimator optical system is designed, the light transmission aperture of the designed collimator system is required to be 320mm, the field angle is 2 degrees, and the focal length is 3600 +/-20 mm.

The following off-axis spherical collimator optical system is designed according to the existing conditions, the structure of which is shown in fig. 1, and the detailed structure is as described above, and the specific parameters are as follows: the aperture diaphragm of the system is 320mm and is positioned on the front surface of the first plano-convex lens 1; the curvature radius of the front and back surfaces of the first plano-convex lens 1 is 6052.616mm and infinity; the distance from the first plano-convex lens 1 to the second plano-concave lens 2 is 34.5 mm; the front and rear surface curvature radius of the second plano-concave lens 2 is-6052.616 mm and infinity, and the lens is inclined at-5.412 °; the distance from the second plano-concave lens 2 to the third spherical mirror 3 is 3167.5 mm; the radius of curvature of the third spherical mirror 3 is-6768.52 mm, and the angle of inclination of the mirror is-3 °.

The x-visual field and the y-visual field of the optical system are both +/-1 degree through detection, the focal length is 3593.15mm, and the design requirements are met. The point alignment chart and the wave aberration chart of the off-axis spherical collimator optical system of the invention in the embodiment 1 are shown in fig. 2-6. As can be seen from FIGS. 2-6, the full field RMS radius is smaller than the Airy spot radius (8.051 μm), reaching the diffraction limit and the image quality is good; the total field of wave aberration is 0.14 λ (λ 632.8nm) at maximum.

Example 2:

when the off-axis spherical surface collimator optical system is designed, the light-passing aperture of the designed collimator system is required to be 200mm, the field angle is 2 degrees, and the focal length is 1900 +/-20 mm.

The following off-axis spherical collimator optical system is designed according to the existing conditions, the structure of which is shown in fig. 1, and the detailed structure is as described above, and the specific parameters are as follows: the aperture diaphragm of the system is 200mm and is positioned on the front surface of the first plano-convex lens 1; the front and back surface curvature radius of the first plano-convex lens 1 is 3156.607mm, infinity, and the inclination of the lens is 0.376 DEG; the distance from the first plano-convex lens 1 to the second plano-concave lens 2 is 21.47 mm; the front and rear surface curvature radius of the second plano-concave lens 2 is-3056.607 mm and infinity, and the lens is inclined at-5.535 °; the distance from the second plano-concave lens 2 to the third spherical mirror 3 is 1506.49 mm; the radius of curvature of the third spherical reflector 3 is-3746.141 mm, and the inclination angle of the reflector is-3.068 degrees.

The x-visual field and the y-visual field of the optical system are both +/-1 degree through detection, the focal length is 1882.14mm, and the design requirements are met. The point alignment chart and the wave aberration chart of the off-axis spherical collimator optical system of the invention in the embodiment 1 are shown in fig. 2-6. As can be seen from FIGS. 2-6, the full field RMS radius is smaller than the Airy spot radius (6.742 μm), reaching the diffraction limit and the image quality is good; the total field of wave aberration is 0.12 λ (λ 632.8nm) at maximum.

In view of the above embodiments, according to the off-axis spherical collimator optical system of the present invention, incident light is transmitted through the first plano-convex lens and the second plano-concave lens, and then reflected by the third reflector to form an image. The elimination of chromatic aberration and the correction of image quality are finished by inclining each lens body to form a certain angle. And parameters of each mirror are optimized, the RMS (root mean square) radius is smaller than the Airy spot radius, and the image quality is good. Compared with the traditional transmission type parallel light tube without central blocking, the off-axis transmission type parallel light tube has wider spectral range and larger field angle, and the x-field angle and the y-field angle are +/-1 degree. The system adopts a global off-axis design, has no central barrier, is simpler in processing and detection, avoids the technical problems of difficulty in processing, assembly and detection, high manufacturing cost and the like of an off-axis reflective collimator optical system with a barrier on the same axis, greatly reduces the processing and detection difficulty and reduces the production cost. Meanwhile, the first plano-convex lens, the second plano-concave lens and the third spherical reflector are all or partially inclined at a certain angle, so that chromatic aberration can be eliminated, the image quality can be corrected, the image quality effect is good, and the field angle is large.

The invention has been described above with reference to the accompanying drawings, it is obvious that the invention is not limited to the specific implementation in the above-described manner, and it is within the scope of the invention to adopt such insubstantial modifications of the inventive concept and solution, or to apply the inventive concept and solution directly to other applications without such modifications.

Claims

1. An off-axis spherical collimator optical system, characterized in that it comprises the first plano-convex lens, the second plano-concave lens, the third spherical reflector, the first plano-convex lens, the second plano-concave lens, the third spherical reflection The curved surfaces of the mirrors are all spherical surfaces, the third spherical reflecting mirrors are set obliquely, and the first plano-convex lens and the second plano-concave lens are set non-parallel.

2. A kind of off-axis spherical collimator optical system according to claim 1 is characterized in that, the x-field angle and y-field angle of the off-axis spherical collimator optical system are both ±1° .

3 . The off-axis spherical collimator optical system according to claim 1 , wherein the incident light transmits through the first plano-convex lens and the second plano-concave lens, and is finally reflected and focused by the third spherical mirror. 4 .

4. An off-axis spherical collimator optical system according to claim 1, wherein the first plano-convex lens and the second plano-concave lens are made of BK7 material, and the third spherical reflector is microcrystalline Glass.

5 . The off-axis spherical collimator optical system according to claim 1 , wherein the curvatures of the curved surfaces of the first plano-convex lens and the second plano-concave lens are opposite numbers to each other. 6 .

6 . The off-axis spherical collimator optical system according to claim 1 , wherein the third reflecting mirror is inclined at a certain angle to complete the off-axis design. 7 .